Real Dictionary

affirm
verb: If an event affirms something, it shows that it is true or exists.
verb: If you affirm that something is true or that something exists, you state firmly and publicly that it is true or exists.

affirm in American English
to declare solemnly, but not under oath; make affirmation
to say positively; declare firmly; assert to be true
intransitive verb: to state something solemnly before a court or magistrate, but without oath
transitive verb: to state or assert positively; maintain as true